WebMD Health Corp. (NASDAQ: WBMD) shares have been volatile in 2015, and are up 9 percent year-to-date.

Leerink Partners’ Steven Wardell maintained an Outperform rating on the company, while raising the price target from $54 to $55.

Medscape is emerging as a killer app on mobile phones, and could drive future growth, Wardell said.

Analyst Steven Wardell commented, “Findings from our ongoing diligence on the trend of physicians shifting to online channels are surprisingly positive.” He added that there seems to be an increasing trend among physicians towards using smartphones in 2015 and the Medscape app could emerge as a killer app. Medscape is WebMD’s physician-facing property.

“Medscape also emerges as a clear leader among other medical apps based on app utilization data,” Wardell wrote.

In the report Leerink Partners noted, “We believe that physicians are the ultimate mobile knowledge worker and that their ultimate mobile tool is coming into focus - a medicalized smartphone such as the iPhone 6 Plus with their EMR app and with the Medscape app on it.”

Wardell believes that the continued growth of the Medscape app is an important determinant of WebMD's value. Pharma advertising would contribute an estimated 58 percent of the company’s sales in 2015, and Medscape is expected to account for about 71 percent of the pharma ad spend. Much of Medscape’s future growth is likely to be driven by the Medscape mobile app.

“We see physicians substituting smartphone equivalents of Continuing Medical Education, medical news, and journal articles for their traditional counterparts as very significant, making mobile apps like Medscape more attractive to pharma brand managers and driving growth, and making offline channels less attractive,” Wardell stated.

The EPS estimate for FY16 and FY17 have been raised from $1.63 to $1.65 and from $1.80 to $1.81, respectively.